Vehicular power transmission control apparatus

ABSTRACT

An apparatus comprises a changeover mechanism which is able to change a connection state of an electric motor output shaft to any one from alternatives consisting of “an IN-Connection State” in which a power transmission path is provided between a transmission input shaft and the electric motor output shaft, “an OUT-Connection State” in which a power transmission path is provided between the transmission output shaft and the electric motor output shaft, and “a neutral state” in which no transmission path therebetween is provided. The changeover is carried out based on a combination (area) of a vehicle speed V and a required driving torque T. As for the changeover, a neutral area is enlarged so that a possibility of selecting the neutral state becomes higher, as a battery temperature is higher, or as an electric motor temperature is higher, or as a remaining battery level is larger.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vehicular power transmission controlapparatus, especially to a vehicular power transmission controlapparatus applied to a vehicle comprising an internal combustion engineand an electric motor as power sources.

2. Description of the Related Art

In these days, a so-called hybrid vehicle comprising an internalcombustion engine and an electric motor (electric motor generator) aspower sources has been developed (refer to, for example, JapaneseUnexamined Patent Application Publication No. 2000-224710). In thehybrid vehicle, the electric motor is used as the power sourcegenerating a driving torque for driving the vehicle together with theinternal combustion engine or by itself, or is used as a power sourcefor starting the internal combustion engine.

Further, the electric motor is used as an electric motor generator forgenerating a regeneration torque to provide a breaking force to thevehicle, or is used as an electric motor generator for generating anelectric power which is supplied to and stored in a battery of thevehicle. These usages of the electric motor can improve a total energyefficiency (fuel consumption) of the vehicle as a whole.

SUMMARY OF THE INVENTION

In the meanwhile, in the hybrid vehicle, there is a case where aconnection state (hereinafter, referred to as an “IN-Connection State”)is used in which a power transmission path between an output shaft ofthe electric motor and an input shaft of a transmission is provided, andthere is another case where another connection state (hereinafter,referred to as an “OUT-Connection State”) is used in which a powertransmission path between the output shaft of the electric motor and anoutput shaft of the transmission (and thus, driving wheels) is providedwithout involving the transmission.

In the “IN-Connection State”, a rotational speed of the output shaft ofthe electric motor with respect to a vehicle speed can be varied bychanging a gear position of the transmission. Accordingly, adjusting thegear position of the transmission can provide an advantage such that therotational speed of the output shaft of the electric motor can easily bemaintained within a range in which an energy conversion efficiency (morespecifically, an efficiency in generating the driving torque, theregeneration torque, or the like) is high.

On the other hand, the “OUT-Connection State” provides an advantage suchthat a power transfer loss can be made smaller, since the powertransmission path does not involve the transmission having a complicatedmechanism. In addition, in the transmission (especially, in atransmission of a type which does not include a torque converter), apower transmission from the input shaft of the transmission to theoutput shaft of the transmission is generally shut off temporarilyduring a gear position shifting operation (during an operation in whichthe gear position is changed). Consequently, a rapid change in anacceleration in a front-rear direction of the vehicle (so-called shiftshock) tends to occur. However, the “OUT-Connection State” allows thedriving torque from the electric motor to be continuously transmitted tothe output shaft of the transmission (and therefore to the drive wheels)even during the gear position shifting operation, and therefore providesan advantage such that the shift shock is suppressed.

In view of the above, the assignee of the present invention has alreadyproposed a changeover mechanism which can change/switch a connectionstate of the output shaft of the electric motor between theIN-Connection State and the OUT-Connection State, in Japanese PatentApplication No. 2007-271556. The changeover mechanism can further changethe connection state of the output shaft of the electric motor to astate in which neither a power transmission path between the outputshaft of the electric motor and the input shaft of the transmission nora power transmission path between the output shaft of the electric motorand the output shaft of the transmission is provided. Hereinafter, thisstate is referred to as a “non-connection state”.

In the meanwhile, in order to protect the battery (typically, asecondary battery) for supplying the electric energy to the electricmotor, and in order to protect the electric motor, etc., it ispreferable that the electric motor be operated/controlled (as the powersource or the electric motor generator) in such a manner that atemperature of the battery and a temperature of the electric motor(e.g., a temperature of a coil portion of the electric motor) do notbecome excessively high. Further, it is unlikely that the battery needsto be further charged, when an amount (hereinafter, referred to as a“remaining battery level, or remaining energy amount of the battery”) ofan energy stored in the battery is sufficiently high.

On the other hand, driving the electric motor as the power source or asthe electric motor generator is stopped in the non-connection state, anda rotation of the output shaft of the electric motor can therefore bestopped, unlike in the IN-Connection State and the OUT-Connection State.Accordingly, in the non-connection state, an increase in the temperatureof the battery as well as of the electric motor can be suppressed, andthe battery can not be charged. In view of the above, it is consideredpreferable to lengthen a time period in which the non-connection stateis selected (or to increase a frequency of selecting the non-connectionstate), when the temperature of the battery is high, the temperature ofthe electric motor is high, or the remaining battery level islarge/high.

An object of the present invention is therefore to provide a vehicularpower transmission control apparatus applied to a vehicle comprising aninternal combustion engine and an electric motor as power sources, thecontrol apparatus being able to appropriately select a connection stateof an output shaft of the electric motor to thereby be able to maintainthe electric motor in good condition or to maintain the battery whichsupplies the electric energy to the electric motor in good condition.

The vehicular power transmission control apparatus according to thepresent invention comprises a transmission, a changeover mechanism,state-representing-amount obtaining means, and control means. Each ofthem will be described hereinafter.

The transmission comprises: an input shaft to provide/realize a powertransmission path between the input shaft of the transmission and anoutput shaft of the internal combustion engine; and an output shaft toprovide/realize a power transmission path between the output shaft ofthe transmission and drive wheels of the vehicle. The transmission isconfigured so as to be able to adjust a ratio (transmission reductionratio) of a rotational speed of the input shaft of the transmission to arotational speed of the output shaft of the transmission. It should benoted that the transmission may be a multiple gear ratio transmissionwhich can realize/achieve each of a plurality of predetermined reductionratios different from one another as the transmission reduction ratio,or may be a continuously variable transmission which can continuously(in a non-stepwise fashion) adjust a reduction ratio as the transmissionreduction ratio.

Further, the transmission may be “a multiple gear ratio transmission ora continuously variable transmission (so-called automatic transmission(AT))” comprising a torque converter and being configured in such amanner that the gear position shifting operation is automaticallyperformed in accordance with a vehicle driving condition, or may be “amultiple gear ratio transmission without the torque converter (so-calledmanual transmission (MT))”. If the transmission is the manualtransmission, the transmission may be, but not limited to, any one ofthe following types.

A type in which the gear position shifting operation is performeddirectly by a force applied to a shift lever from a driver.

A type in which the gear position shifting operation is performed by adrive force generated by an actuator which is driven in response to asignal indicative of a position of the shift lever which the driveroperates.

A type in which the gear position shifting operation can beautomatically performed by a drive force generated by an actuator whichis automatically driven in accordance with the vehicle drivingcondition, without depending on an operation of the shift lever by thedriver (i.e., a so-called automated manual transmission).

The changeover mechanism can change a connection state of the outputshaft of the electric motor to any one from alternatives comprising twoor more of an IN-Connection State, an OUT-Connection State, and anon-connection state as an essential state (i.e., the non-connectionstate must be included),

-   -   the IN-Connection State (input-side-connection state) being a        state in which a power transmission path is provided between the        output shaft of the electric motor and the input shaft of the        transmission,    -   the OUT-Connection State (output-side-connection state) being a        state in which a power transmission path is provided between the        output shaft of the electric motor and the drive wheels without        involving the transmission, and    -   the non-connection state being a state in which neither a power        transmission path between the output shaft of the electric motor        and the input shaft of the transmission, nor a power        transmission path between the output shaft of the electric motor        and the output shaft of the transmission (i.e., the drive        wheels) is provided. That is, the changeover mechanism may be,        but not limited to, one of the followings.

A changeover mechanism which can change the connection state of theoutput shaft of the electric motor into any one of the IN-ConnectionState and the non-connection state, only (i.e. which can realize any onefrom the IN-Connection State and the non-connection state, only).

A changeover mechanism which can change the connection state of theoutput shaft of the electric motor into any one of the OUT-ConnectionState and the non-connection state, only (i.e. which can realize any onefrom the OUT-Connection State and the non-connection state, only).

A changeover mechanism which can change the connection state of theoutput shaft of the electric motor into any one of the IN-ConnectionState, the OUT-Connection State, and the non-connection state (i.e.which can realize any one from the IN-Connection State, theOUT-connection state, and the non-connection state).

In the IN-Connection State, a ratio (hereinafter, referred to as a“first reduction ratio”) of the rotational speed of the output shaft ofthe electric motor to the rotational speed of the input shaft of thetransmission is generally fixed to a constant (e.g., 1). Hereinafter, aproduct of “the first reduction ratio” and “the transmission reductionratio” is referred to as an “IN-connection reduction ratio”. “TheIN-connection reduction ratio” varies in accordance with a change in“the transmission reduction ratio” caused by the gear position shiftingoperation of the transmission. On the other hand, in the OUT-ConnectionState, a ratio of the rotational speed of the output shaft of theelectric motor to a rotational speed of the output shaft of thetransmission is generally fixed to a constant (e.g., a value larger than1, a value close to the transmission reduction ratio corresponding to a2nd gear position, or the like). Hereinafter, this ratio is referred toas an “OUT-connection reduction ratio”. “The OUT-connection reductionratio” is kept constant, even when “the transmission reduction ratio”varies. It should be noted that a ratio of the rotational speed of theoutput shaft of the internal combustion engine to a rotational speed ofthe input shaft of the transmission is generally set at a constant(e.g., 1).

The state-representing-amount obtaining means obtains, as anstate-representing-amount, one or more from a temperature of a batterywhich supplies an electric energy to the electric motor, a temperatureof the electric motor, and an amount (remaining battery level) of anenergy stored in the battery.

The control means selects a target connection state of the output shaftof the electric motor from the connection states which the changeovermeans can realize, based on the state-representing-amount and aparameter indicative of a running condition of the vehicle other thanthe state-representing-amount, in such a manner that a possibility ofselecting the non-connection state is varied (i.e., an ease by which thenon-connection state is selected is varied, or a time period in whichthe non-connection state is selected is varied, or a frequency ofselecting the non-connection state varies) in accordance with thestate-representing-amount. The control means further controls thechangeover means in such a manner that an actual connection state of theoutput shaft of the electric motor coincides with the selectedconnection state (as the target connection state). Specifically, thepossibility of selecting the non-connection state is varied inaccordance with any one of the temperature of the battery itself, thetemperature of the electric motor itself, the remaining battery levelitself, and a combination including two or more from the temperature ofthe battery, the temperature of the electric motor, and the remainingbattery level, and the like. It should be noted that, in (under) thenon-connection state, driving the electric motor as the power source anddriving the electric motor as the electric motor generator are stopped,and a rotation of the output shaft of the electric motor can thereforebe stopped.

Examples of the parameter indicative of the running condition of thevehicle include a value correlating with the vehicle speed (speed of thevehicle), a value correlating with a required driving torque obtainedbased on an operation of an acceleration operating member by the driverof the vehicle, and so on. Examples of the value correlating with thevehicle speed include the vehicle speed itself, the rotational speed ofthe input shaft of the transmission, the rotational speed of the outputshaft of the internal combustion engine, and the rotational speed of theoutput shaft of the electric motor, and so on. Examples of the valuecorrelating with the required driving torque include an operating amountof the acceleration operating member, and an opening degree of athrottle valve disposed in an intake passage of the internal combustionengine.

According to the configuration described above, the possibility ofselecting the non-connection state varies in accordance with thestate-representing-amount. Accordingly, for example, a time period inwhich the non-connection state is selected/realized can be made longer(the frequency of selecting the non-connection state can be increased),when the temperature of the battery is high, the temperature of theelectric motor is high, or the remaining battery level is large (high).Consequently, a time period lengthens in which the rotation of theoutput shaft of the electric motor is stopped by stopping driving theelectric motor as the power source and driving the electric motor as theelectric motor generator. Accordingly, the increase in the temperatureof the battery as well as the increase in the temperature of theelectric motor can be suppressed. Further, the battery is not chargedunnecessarily. That is, the electric motor and the battery can bemaintained in good conditions.

More specifically, the control means is preferably configured so as toadjust a threshold in such a manner that the threshold is smaller, asthe temperature of the battery is higher, or as the temperature of theelectric motor is higher, or as the remaining battery level islarger/higher, in a case where the control means changes the actualconnection state of the output shaft of the electric motor from aconnection state other than the non-connection state (i.e., theIN-Connection State or the OUT-Connection State) to the non-connectionstate, when the value correlating with a speed of the vehicle passesover/through the threshold while the value correlating with a speed ofthe vehicle is increasing. According to the configuration describedabove, during the vehicle speed is increasing, a timing at which thechangeover (shifting) from the connection state other than thenon-connection state to the non-connection state is carried out comesearlier, as the temperature of the battery is higher, or as thetemperature of the electric motor is higher, or as the remaining batterylevel is larger/higher. That is, a time period in which thenon-connection state is selected/realized lengthens. Consequently, theincrease in the temperature of the battery as well as the increase inthe temperature of the electric motor can be suppressed, and theunnecessary further charge of the battery can be also avoided.

Similarly, the control means is preferably configured so as to adjust athreshold in such a manner that the threshold becomes smaller, as thetemperature of the battery is higher, or as the temperature of theelectric motor is higher, or as the remaining battery level islarger/higher, in a case where the control means changes the actualconnection state of the output shaft of the electric motor from aconnection state other than the non-connection state (i.e., theIN-Connection State or the OUT-Connection State) to the non-connectionstate, when the value correlating with a required driving torque passesover/through the threshold while the value correlating with a requireddriving torque is increasing, the value correlating with a requireddriving torque being a value obtained based on an operation applied toan acceleration operating member by the driver of the vehicle. Accordingto the configuration described above, during the required driving torqueis increasing, a timing at which the changeover (shifting) from theconnection state other than the non-connection state to thenon-connection state is carried out comes earlier, as the temperature ofthe battery is higher, or as the temperature of the electric motor ishigher, or as the remaining battery level is larger/higher. That is, atime period in which the non-connection state is selected/realizedlengthens. Consequently, the increase in the temperature of the batteryas well as the increase in the temperature of the electric motor can besuppressed, and the unnecessary charge of the battery can be alsoavoided.

In these cases, the control means may be configured so as to always fixthe actual connection state of the output shaft of the electric motor tothe non-connection state, when the temperature of the battery is higherthan or equal to a first predetermined value, or when the temperature ofthe electric motor is higher than or equal to a second predeterminedvalue. According to the configuration described above, thenon-connection state is always selected, when the temperature of thebattery or the temperature of the electric motor is considerably high.Consequently, a further increase in the temperature of the battery aswell as a further increase in the temperature of the electric motor canbe suppressed with certainty.

Further, the control means may preferably be configured so as to,

-   -   change the actual connection state of the output shaft of the        electric motor from the IN-Connection State (hereinafter,        referred to as a “first IN-Connection State”) to the        OUT-Connection State, when the value correlating with a speed of        the vehicle passes over a first threshold while the value        correlating with a speed of the vehicle is increasing;    -   change the actual connection state of the output shaft of the        electric motor from the OUT-Connection State to the        IN-Connection State (hereinafter, referred to as a “second        IN-Connection State”), when the value correlating with a speed        of the vehicle passes over a second threshold larger than the        first threshold while the value correlating with a speed of the        vehicle is increasing;    -   change the actual connection state of the output shaft of the        electric motor from the (second) IN-Connection State to the        non-connection state, (1) when the value correlating with a        speed of the vehicle passes over a third threshold larger than        the second threshold while the value correlating with a speed of        the vehicle is increasing in a case where the value correlating        with a required driving torque is larger than a fourth        threshold, or (2) when the value correlating with a required        driving torque passes over the fourth threshold while the value        correlating with a required driving torque is increasing in a        case where the value correlating with a speed of the vehicle is        larger than the third threshold.

In this case, it is preferable that the control means be configured soas to adjust the third threshold and/or the fourth threshold in such amanner that the third threshold becomes smaller and the fourth thresholdbecomes smaller, as the temperature of the battery is higher, or as thetemperature of the electric motor is higher, or as the remaining batterylevel is larger/higher. It should be noted that each of the first,second, and third thresholds may be a value varying depending on therequired driving torque, or be a constant. The fourth threshold may be avalue varying depending on the value correlating with the speed of thevehicle, or be a constant.

According to the configuration described above, during the vehicle speedis increasing, a timing at which the changeover (shifting) from the(second) IN-Connection State to the non-connection state is carried outcomes earlier, as the temperature of the battery is higher, or as thetemperature of the electric motor is higher, or as the remaining batterylevel is larger/higher. Further, during the required driving torque isincreasing, a timing at which the changeover (shifting) from the(second) IN-Connection State to the non-connection state is carried outcomes earlier, as the temperature of the battery is higher, or as thetemperature of the electric motor is higher, or as the remaining batterylevel is larger/higher. That is, a time period in which thenon-connection state is selected lengthens (becomes longer).Consequently, the increase in the temperature of the battery as well asthe increase in the temperature of the electric motor can be suppressed,and the unnecessary further charge of the battery can be also avoided.

In this case, the control means may be configured so as to fix theactual connection state of the output shaft of the electric motor to thenon-connection state, in a condition in which the value correlating witha speed of the vehicle is larger than or equal to the second threshold,(1) when the temperature of the battery is higher than or equal to afirst predetermined value, or (2) when the temperature of the electricmotor is higher than or equal to a second predetermined value. Accordingto the configuration described above, when the temperature of thebattery or the temperature of the electric motor is considerably high, atime period in which the (second) IN-Connection State isselected/realized disappears, and a period in which the non-connectionstate is selected/realized therefore lengthens. Consequently, a furtherincrease in the temperature of the battery as well as a further increasein the temperature of the electric motor can be suppressed withcertainty.

Furthermore, the control means may be configured so as to always fix theactual connection state of the output shaft of the electric motor to thenon-connection state, irrespective of (without depending on) the valuecorrelating with a speed of the vehicle and the value correlating with arequired driving torque, (1) when the temperature of the battery ishigher than or equal to a first predetermined value, or (2) when thetemperature of the electric motor is higher than or equal to a secondpredetermined value. According to the configuration described above,when the temperature of the battery or the temperature of the electricmotor is considerably high, the non-connection state is alwaysselected/realized. Consequently, a further increase in the temperatureof the battery as well as a further increase in the temperature of theelectric motor can be suppressed with certainty.

It is preferable that the vehicular power transmission control apparatusaccording to the present invention be applied to the vehicle having theautomated manual transmission described above as the transmission. Inthis case, a clutch mechanism is provided between the output shaft ofthe internal combustion engine and the input shaft of the transmission.The clutch mechanism can shut (break/terminate) or provide (realize) apower transmission path between the output shaft of the internalcombustion engine and the input shaft of the transmission. In addition,in this case, the transmission does not comprise the torque converter,but is the multiple gear ratio transmission which can realize any one ofa plurality of predetermined reduction ratios different from one anotheras the transmission reduction ratio. Further, the control means isconfigured so as to control, based on the driving condition (e.g., thevehicle speed and the required driving torque) of the vehicle, shuttingand providing of the power transmission path by the clutch mechanism,and the transmission reduction ratio (the gear position).

BRIEF DESCRIPTION OF THE DRAWINGS

Various other objects, features and many of the attendant advantages ofthe present invention will be readily appreciated as the same becomesbetter understood by reference to the following detailed description ofthe preferred embodiments when considered in connection with theaccompanying drawings, in which:

FIG. 1 is a schematic view of a vehicle which mounts a vehicular powertransmission control apparatus according to an embodiment of the presentinvention;

FIG. 2A is a schematic view showing one of three states which the firstchangeover mechanism in the transmission shown in FIG. 1 can realize;

FIG. 2B is a schematic view showing one of three states which the firstchangeover mechanism in the transmission shown in FIG. 1 can realize;

FIG. 2C is a schematic view showing one of three states which the firstchangeover mechanism in the transmission shown in FIG. 1 can realize;

FIG. 3A is a schematic view showing one of three states which the secondchangeover mechanism in the transmission shown in FIG. 1 can realize;

FIG. 3B is a schematic view showing one of three states which the secondchangeover mechanism in the transmission shown in FIG. 1 can realize;

FIG. 3C is a schematic view showing one of three states which the secondchangeover mechanism in the transmission shown in FIG. 1 can realize;

FIG. 4A is a schematic view showing one of two states which the thirdchangeover mechanism in the transmission shown in FIG. 1 can realize;

FIG. 4B is a schematic view showing one of two states which the thirdchangeover mechanism in the transmission shown in FIG. 1 can realize;

FIG. 5 is a graph showing a relation among a rotational speed, a maximumtorque, and an energy conversion efficiency, of the motor generatorshown in FIG. 1;

FIG. 6A is a schematic view showing one of three states which thechangeover mechanism shown in FIG. 1 can realize;

FIG. 6B is a schematic view showing one of three states which thechangeover mechanism shown in FIG. 1 can realize;

FIG. 6C is a schematic view showing one of three states which thechangeover mechanism shown in FIG. 1 can realize;

FIG. 7 is a graph showing a relation among a vehicle speed and arequired driving torque as well as a gear position of the transmissionto be selected, in the embodiment shown in FIG. 1;

FIG. 8 is a graph showing a relation among the vehicle speed and therequired driving torque, as well as a connection state to be selected inthe changeover mechanism, in the embodiment shown in FIG. 1;

FIG. 9 is a graph showing a relation between a temperature of a batteryand a shift amount of a boundary line, in the embodiment shown in FIG.1;

FIG. 10 is a graph showing a relation between a temperature of a M/G(electric motor) and a shift amount of a boundary line, in theembodiment shown in FIG. 1;

FIG. 11 is a graph showing a relation between a remaining battery leveland a shift amount of a boundary line, in the embodiment shown in FIG.1;

FIG. 12 is a graph showing a relation among a vehicle speed and arequired driving torque as well as a selected connection state realizedby a changeover mechanism, when the temperature of the M/G or thetemperature of the battery is higher or equal to a predetermined value,in a modification of the embodiment shown in FIG. 1;

FIG. 13 is a graph showing a relation among a vehicle speed and arequired driving torque as well as a selected connection state realizedby a changeover mechanism, when the temperature of the M/G or thetemperature of the battery is higher or equal to a predetermined value,in a modification of the embodiment shown in FIG. 1;

FIG. 14 is a graph showing a relation between a temperature of a batteryand a shift amount of a boundary line, in a modification of theembodiment shown in FIG. 1;

FIG. 15 is a graph showing a relation between a temperature of a M/G(electric motor) and a shift amount of a boundary line, in amodification of the embodiment shown in FIG. 1;

FIG. 16 is a graph showing a relation between a remaining battery leveland a shift amount of a boundary line, in a modification of theembodiment shown in FIG. 1;

FIG. 17 is a graph showing a map A among a plurality of maps, eachdefining a relation among the vehicle speed and the required drivingtorque as well as the selected connection state realized by thechangeover mechanism, in a modification of the embodiment shown in FIG.1;

FIG. 18 is a graph showing a map B among a plurality of the maps, eachdefining the relation among the vehicle speed and the required drivingtorque as well as the selected connection state realized by thechangeover mechanism, in a modification of the embodiment shown in FIG.1;

FIG. 19 is a graph showing a map C among a plurality of the maps, eachdefining the relation among the vehicle speed and the required drivingtorque as well as the selected connection state realized by thechangeover mechanism, in a modification of the embodiment shown in FIG.1;

FIG. 20 is a graph showing a map D among a plurality of the maps, eachdefining the relation among the vehicle speed and the required drivingtorque as well as the selected connection state realized by thechangeover mechanism, in a modification of the embodiment shown in FIG.1;

FIG. 21 is a graph showing a map E among a plurality of the maps, eachdefining the relation among the vehicle speed and the required drivingtorque as well as the selected connection state realized by thechangeover mechanism, in a modification of the embodiment shown in FIG.1; and

FIG. 22 shows a relation between one of “the temperature of the battery,the temperature of the electric motor, and the remaining battery level”and “a map” to be selected among the maps A-E.

DETAILED DESCRIPTION OF THE INVENTION

Next will be described embodiments of a vehicular power transmissioncontrol apparatus according to the present invention with reference tothe drawings.

(Configuration)

FIG. 1 shows a schematic configuration of a vehicle mounting a vehicularpower transmission control apparatus (hereinafter, referred to as a“present apparatus”) according to an embodiment of the presentinvention. The present apparatus is applied to the vehicle comprising,as its power sources, an internal combustion engine and a motorgenerator. The vehicle comprises a so-called automated manualtransmission, which uses a multiple gear ratio transmission, but whichdoes not have a torque converter.

The vehicle comprises the engine (E/G) 10, the transmission (T/M) 20, aclutch (C/T) 30, the motor generator (M/G) 40, and a changeovermechanism 50. The E/G 10 is one of well-known internal combustionengines, including a gasoline engine which uses a gasoline as a fuel anda diesel engine which uses a light diesel oil as a fuel. An output shaftA1 of the E/G 10 is connected to an input shaft A2 of the T/M 20 throughthe C/T 30.

The T/M 20 is one of well-known multiple gear ratio transmission. TheT/M 20 has five gear positions (a 1st, a 2nd, a 3rd, a 4th, and a 5thpositions) as forward gear positions. The T/M 20 does not comprise atorque convertor. That is, the T/M 20 can set a transmission reductionratio Gtm at any one of five ratios. The transmission reduction ratioGtm is a ratio of a rotational speed of the input shaft A2 to arotational speed of the output shaft A3. The gear positions arechanged/shifted by controlling a first, a second, and a third changeovermechanisms 21, 22, and 23.

More specifically, as shown in FIG. 2, the first changeover mechanism 21comprises a gear G11 axially supported by and rotatably immovablerelative to the input shaft A2, a gear G12 axially supported by androtatably movable relative to the output shaft A3 so as to always meshwith the gear G11, a gear G21 axially supported by and rotatablyimmovable relative to the input shaft A2, and a gear G22 axiallysupported by and rotatably movable relative to the output shaft A3 so asto always mesh with the gear G21. Further, the first changeovermechanism 21 comprises a connection piece 21 a which rotates integrallywith the output shaft A3, a connection piece 21 b which rotatesintegrally with the gear G12, a connection piece 21 c which rotatesintegrally with the gear G22, a sleeve 21 d, and an actuator 24.

The sleeve 21 d is provided so as to be movable in an axial direction ofthe output shaft A3. A position of the sleeve 21 d along the axialdirection is controlled by the actuator 24. The sleeve 21 d is able tobe spline-engaged with the connection pieces 21 a, 21 b, and 21 c. Whenthe sleeve 21 d is at a non-connection position (neutral position) shownin FIG. 2A, the sleeve 21 d spline-engages only with the connectionpiece 21 a, and both of the gears G12 and G22 are therefore rotatablymovable relative to the output shaft A3. When the sleeve 21 d is at a1st-gear-position-connection position shown in FIG. 2B, the sleeve 21 dspline-engages with the connection pieces 21 a and 21 b. Accordingly,the gear G12 is rotatably immovable relative to the output shaft A3,whereas the gear G22 is rotatably movable relative to the output shaftA3. When the sleeve 21 d is at a 2nd-gear-position-connection positionshown in FIG. 2C, the sleeve 21 d spline-engages with the connectionpieces 21 a and 21 c. Accordingly, the gear G22 is rotatably immovablerelative to the output shaft A3, whereas the gear G12 is rotatablymovable relative to the output shaft A3.

As shown in FIGS. 3A to 3C, the second changeover mechanism 22 comprisesa gear G31 axially supported by and rotatably movable relative to theinput shaft A2, a gear G32 axially supported by and rotatably immovablerelative to the output shaft A3 so as to always mesh with the gear G31,a gear G41 axially supported by and rotatably movable relative to theinput shaft A2, and a gear G42 axially supported by and rotatablyimmovable relative to the output shaft A3 so as to always mesh with thegear G41. Further, the second changeover mechanism 22 comprises aconnection piece 22 a which rotates integrally with the input shaft A2,a connection piece 22 b which rotates integrally with the gear G31, aconnection piece 22 c which rotates integrally with the gear G41, asleeve 22 d, and an actuator 25.

The sleeve 22 d is provided so as to be movable in an axial direction ofthe input shaft A2. A position of the sleeve 22 d along the axialdirection is controlled by the actuator 25. The sleeve 22 d is able tospline-engage with the connection pieces 22 a, 22 b, and 22 c. When thesleeve 22 d is at a non-connection position (neutral position) shown inFIG. 3A, the sleeve 22 d spline-engages only with the connection piece22 a, and both of the gears G31 and G41 are therefore rotatably movablerelative to the input shaft A2. When the sleeve 22 d is at a3rd-gear-position-connection position shown in FIG. 3B, the sleeve 22 dspline-engages with the connection pieces 22 a and 22 b. Accordingly,the gear G31 is rotatably immovable relative to the input shaft A2,whereas the gear G41 is rotatably movable relative to the input shaftA2. When the sleeve 22 d is at a 4th-gear-position-connection positionshown in FIG. 3C, the sleeve 22 d spline-engages with the connectionpieces 22 a and 22 c. Accordingly, the gear G41 is rotatably immovablerelative to the input shaft A2, whereas the gear G31 is rotatablymovable relative to the input shaft A2.

As shown in FIGS. 4A and 4B, the third changeover mechanism 23 comprisesa gear G51 axially supported by and rotatably movable relative to theinput shaft A2, a gear G52 axially supported by and rotatably immovablerelative to the output shaft A3 so as to always mesh with the gear G51.Further, the third changeover mechanism 23 comprises a connection piece23 a which rotates integrally with the input shaft A2, a connectionpiece 23 b which rotates integrally with the gear G51, a sleeve 23 d,and an actuator 26.

The sleeve 23 d is provided so as to be movable in the axial directionof the input shaft A2. A position of the sleeve 23 d along the axialdirection is controlled by the actuator 26. The sleeve 23 d is able tospline-engage with the connection pieces 23 a and 23 b. When the sleeve23 d is at a non-connection position (neutral position) shown in FIG.4A, the sleeve 23 d spline-engages only with the connection piece 23 a,and the gears G51 is therefore rotatably movable relative to the inputshaft A2. When the sleeve 23 d is at a 5th-gear-position-connectionposition shown in FIG. 4B, the sleeve 23 d spline-engages with theconnection pieces 23 a and 23 b. Accordingly, the gear G51 is rotatablyimmovable relative to the input shaft A2.

When the gear position is set at “the 1st gear position”, the changeovermechanisms 21, 22, and 23 are controlled to “the1st-gear-position-connection position”, “the neutral position”, and “theneutral position”, respectively. Consequently, a power transmission pathis provided/realized between the input shaft A2 and the output shaft A3through the gears G11, and G12, and the transmission reduction ratio Gtmbecomes equal to (the number of teeth of the gear G12)/(the number ofteeth of the gear G11). This value is also expressed as Gtm(1). When thegear position is set at “the 2nd gear position”, the changeovermechanisms 21, 22, and 23 are controlled to “the2nd-gear-position-connection position”, “the neutral position”, and “theneutral position”, respectively. Consequently, a power transmission pathis provided/realized between the input shaft A2 and the output shaft A3through the gears G21, and G22, and the transmission reduction ratio Gtmbecomes equal to (the number of teeth of the gear G22)/(the number ofteeth of the gear G21). This value is also expressed as Gtm(2).

When the gear position is set at “the 3rd gear position”, the changeovermechanisms 21, 22, and 23 are controlled to “the neutral position”, “the3rd-gear-position-connection position”, and “the neutral position”,respectively. Consequently, a power transmission path isprovided/realized between the input shaft A2 and the output shaft A3through the gears G31, and G32, and the transmission reduction ratio Gtmbecomes equal to (the number of teeth of the gear G32)/(the number ofteeth of the gear G31). This value is also expressed as Gtm(3). When thegear position is set at “the 4th gear position”, the changeovermechanisms 21, 22, and 23 are controlled to “the neutral position”, “the4th-gear-position-connection position”, and “the neutral position”,respectively. Consequently, a power transmission path isprovided/realized between the input shaft A2 and the output shaft A3through the gears G41, and G42, and the transmission reduction ratio Gtmbecomes equal to (the number of teeth of the gear G42)/(the number ofteeth of the gear G41). This value is also expressed as Gtm(4).

When the gear position is set at “the 5th gear position”, the changeovermechanisms 21, 22, and 23 are controlled to “the neutral position”, “theneutral position”, and “the 5th-gear-position-connection position”,respectively. Consequently, a power transmission path isprovided/realized between the input shaft A2 and the output shaft A3through the gears G51, and G52, and the transmission reduction ratio Gtmbecomes equal to (the number of teeth of the gear G52)/(the number ofteeth of the gear G51). This value is also expressed as Gtm(5). In thismanner, in the T/M 20, the actuators 24, 25, and 26 are controlled sothat the transmission reduction ratio Gtm can be set at one of the fivereduction ratios. Here, a relation Gtm(1)>Gtm(2)>Gtm(3)>Gtm(4)>Gtm(5) issatisfied.

The C/T 30 comprises a well-known structure and is configured in such amanner that the C/T 30 can break (or shut) and provide (or realize,form) a power transmission path between the output shaft A1 of the E/G10 and the input shaft A2 of the T/M 20. In the vehicle, a clutch pedalis not provided. A state of the C/T 30 is controlled only by an actuator31. When the C/T 30 is in a connection state, the output shaft A1 of theE/G 10 and the input shaft A2 of the T/M 20 rotate at the samerotational speed.

The M/G 40 comprises a well-known structure (e.g., an AC synchronousmotor), and is configured in such a manner that the a rotor 41 rotatesintegrally with an output shaft A4 which is provided coaxially with andis rotatably movable relative to the input shaft A2 of the T/M 20. TheM/G 40 functions as the power source as well as the electric powergenerator.

FIG. 5 shows a relation among the rotational speed of the output shaftA4 of the M/G 40, a maximum torque which the M/G 40 can generate, andthe energy conversion efficiency (torque generating efficiency). Asshown in FIG. 5, the maximum torque which the M/G 40 can generate isconstant when the rotational speed of the output shaft A4 is smallerthan a certain value, and decreases as the rotational speed increaseswhen the rotational speed is larger than the certain value. Further, theM/G 40 does not generate any torque when the rotational speed is largerthan an allowable rotational speed. In addition, the energy conversionefficiency (torque generating efficiency) can become the largest whenthe rotational speed of the output shaft A4 is at another certain value,and becomes smaller as an absolute value of a difference between therotational speed and the another certain value is larger. That is, theenergy conversion efficiency decreases as the rotational speed comescloser to the allowable rotational speed.

The changeover mechanism 50 is a mechanism which changes (over) aconnection state of the output shaft A4 of the M/G 40. The changeovermechanism 50 comprises a connection piece 51 which rotates integrallywith the rotor 41, a connection piece 52 which rotates integrally withthe input shaft A2 of the T/M 20, a connection piece 53 axiallysupported by and rotatably movable relative to the input shaft A2, asleeve 54, and an actuator 55. Further, the changeover mechanism 50comprises a gear Go1 which rotates integrally with the connection piece53 and is axially supported by and rotatably movable relative to theinput shaft A2, and a gear Go2 which rotates integrally with the outputshaft A3 of the T/M 20 and always meshes with the gear Go1.

The sleeve 54 is provided so as to be movable in the axial direction ofthe input shaft A2 of the T/M 20. A position of the sleeve 54 along theaxial direction is controlled by the actuator 55. The sleeve 54 is ableto spline-engage with the connection pieces 51, 52, and 53.

When the sleeve 54 is controlled to an IN-Connection position shown inFIG. 6A, the sleeve 54 spline-engages with the connection pieces 51 and52. Accordingly, the output shaft A4 of the M/G 40 and the input shaftA2 of the T/M 20 become rotatably immovable to each other. Thisprovides/realizes a power transmission path between the input shaft A2of the T/M 20 and the output shaft A4 of the M/G 40. This state isreferred to as an “IN-Connection State”.

In the IN-Connection State, a ratio of a rotational speed of the outputshaft A4 of the M/G 40 to a rotational speed of the input shaft A2 ofthe T/M 20 is referred to as a “first reduction ratio G1”, and a product(G1·Gtm) of the first reduction ratio G1 and the transmission reductionratio Gtm is referred to as an “IN-connection reduction ratio Gin”. Inthe present example, G1=1, and therefore Gin=Gtm. That is, theIN-connection reduction ratio Gin varies in accordance with the gearposition of the T/M 20.

When the sleeve 54 is controlled to an OUT-Connection position shown inFIG. 6B, the sleeve 54 spline-engages with the connection pieces 51 and53. Accordingly, the output shaft A4 of the M/G 40 and the gear Go1become rotatably immovable to each other. This provides/realizes a powertransmission path between the output shaft A3 of the T/M 20 and theoutput shaft A4 of the M/G 40 through the gear Go1 and the gear Go2,without involving the T/M 20. This state is referred to as an“OUT-Connection State”.

In the OUT-Connection State, a ratio of a rotational speed of the outputshaft A4 of the M/G 40 to a rotational speed of the output shaft A3 ofthe T/M 20 is referred to as an “OUT-connection reduction ratio Gout”.In the present example, the OUT-connection reduction ratio Gout is equalto (the number of teeth of the gear Go2)/(the number of teeth of thegear Go1) and thus is constant. That is, the OUT-connection reductionratio Gout does not vary in accordance with a change in the gearposition of the T/M 20. In the present example, the OUT-connectionreduction ratio Gout is set at a value which is roughly equal to theGtm(2), for example.

When the sleeve 54 is controlled to a non-connection position (neutralposition) shown in FIG. 6C, the sleeve 54 spline-engages only with theconnection piece 51. Accordingly, both the input shaft A2 and the gearGo1 are rotatably movable relative to the output shaft A4. Accordingly,neither a power transmission path between the output shaft A3 of the T/M20 and the output shaft A4 nor a power transmission path between theinput shaft A2 of the T/M 20 and the output shaft A4 is provided. Thisstate is referred to as a “non-connection state (neutral state)”.

As described above, the changeover mechanism 50 selectively changes theconnection state of the output shaft A4 of the M/G 40 into one of “theIN-Connection State”, “the OUT-Connection State”, and “the neutralstate”.

As shown in FIG. 1, a gear Gf1 is axially supported by and rotatablyimmovable relative to the output shaft A3 of the T/M 20. The gear Gf1always meshes with a gear Gf2. The gear Gf2 is connected with adifferential mechanism D/F comprising one of well-known configurations.The differential mechanism D/F is connected a pair of drive wheelsincluding a left drive wheel and a right drive wheel. It should be notedthat the (the number of teeth of the gear Gf2)/(the number of teeth ofthe gear Gf1) corresponds to a so-called final reduction ratio.

The present apparatus further comprises a wheel speed sensor 61 whichdetects a wheel speed of the drive wheels, an acceleration pedal openingdegree sensor 62 which detects an operation amount of an accelerationpedal AP, a shift position sensor 63 which detects a position of a shiftlever SF, an battery temperature sensor 68 which detects a temperatureof the battery (secondary battery B) for supplying an electric energy tothe M/G 40, and a M/G temperature sensor 69 which detects a temperatureof the M/G 40 (specifically, a temperature of a coil portion of the M/G40).

The present apparatus further comprises an electronic control unit ECU70. The ECU 70 controls the actuators 24, 25, 26, 31, and 55, based oninformation and so on from the sensors 61-63, 68 and 69 to therebycontrol the gear position of the T/M 20 and the state of the Ca 30.Further, the ECU 70 controls the output (driving torque) of each of theE/G 10 and M/G 40, and a charging condition of the battery B, etc.

The gear position of the T/M 20 is controlled based on a vehicle speed Vobtained from the wheel speed sensor 61, a required driving torque Tcalculated based on the operation amount of the acceleration pedal APobtained from the acceleration pedal opening degree sensor 62, and theshift lever position SF obtained from the shift position sensor 63. Whenthe shift lever position SF is at a position corresponding to a “manualmode”, the gear position of the T/M 20 is basically set at a gearposition selected by the driver who operates the shift lever SF. On theother hand, when the shift lever position SF is at a positioncorresponding to an “automatic mode”, the gear position of the T/M 20 isautomatically controlled to one of the 1st to the 5th gear positions inaccordance with “a combination of the vehicle speed V and the requireddriving torque T” and “the Map” shown in FIG. 7, even when the shiftlever SF is not operated.

In FIG. 7, each of the solid lines shows each of boundary lines whichcauses a shift up (a shift up operation, or a gear position changeoperation to decrease the transmission reduction ratio Gtm) with anincrease in the vehicle speed V, and each of the dashed lines shows eachof boundary lines which causes a shift down (a shift down operation, ora gear position change operation to increase the transmission reductionratio Gtm) with a decrease in the vehicle speed V. The reason why adifference Δx is provided between the each solid line and the eachdashed line as shown is to suppress an occurrence of a case (so-calledhunting) in which the shift up and the shift down are performedfrequently even though they are not necessary, when the vehicle speed Vfluctuates (increases and decreases) around each of the valuescorresponding the solid lines.

A state of the C/T 30 is generally kept at the connection state, and istemporarily changed from the connection state to the non-connectionstate during the shift up operation and the shift down operation, and soon.

The M/G 40 is used as a driving power source generating a driving torquefor driving the vehicle together with the E/G 10 or by itself, or isused as a power source for starting the E/G 10. Further, the M/G 40 isused as an electric motor generator for generating a regeneration torqueto provide a breaking force to the vehicle, or is used as an electricmotor generator for generating an electric power which is supplied toand stored in a battery (not shown) of the vehicle.

When the M/G 40 is used as the driving power source for driving thevehicle, a distribution between the output (driving torque) of the E/G10 and the output (driving torque) of the M/G 40 is adjusted in such amanner that a sum of the driving torque transmitted to the drive wheelsbased on the output of the E/G 10 and the driving torque transmitted tothe drive wheels based on the output of the M/G 40 coincides with therequired driving torque T, according to one of well-known methods.

(Selection of the Connection State of the Output Shaft A4 of the M/G 40)

Next will be described how to select the (a target) connection state ofthe output shaft A4 of the M/G 40. The connection state of the outputshaft A4 of the M/G 40 is automatically selected in accordance with “acombination of the vehicle speed V and the required driving torque T”and the map shown in FIG. 8.

As shown in FIG. 8, four areas (or regions) are defined with respect to“the combination of the vehicle speed V and the required driving torqueT”, i.e., a first IN-Connection area, an OUT-Connection area, a secondIN-Connection area, and a neutral area (non-connection area). In thefirst and second IN-Connection areas, “the In-Connection State” isselected. In the OUT-Connection area, “the OUT-Connection State” isselected. In the neutral area, “the neutral-connection state(non-connection state)” is selected. Hereinafter, “the IN-ConnectionStates” corresponding to the first IN-Connection area and the secondIN-Connection area are referred separately to as “a first IN-ConnectionState” and “a second IN-Connection State”, respectively.

A changeover from “the first IN-Connection State” to “the OUT-ConnectionState” is carried out, when the vehicle speed V passes through/over theboundary line L1 (corresponding to “the first threshold” describedabove) while the vehicle speed V is increasing. A changeover from “theOUT-Connection State” to “the second IN-Connection State” is carriedout, when the vehicle speed V passes through/over the boundary line L2(corresponding to “the second threshold” described above) while thevehicle speed V is increasing. A changeover from “the secondIN-Connection State” to “the neutral state” is carried out, (1) when thevehicle speed V passes through/over the boundary line L3 (correspondingto “the third threshold” described above) while the vehicle speed V isincreasing in a case where the required driving torque T is larger thanthe boundary line L4 (corresponding to “the fourth threshold” describedabove), or (2) when the required driving torque T passes through/overthe boundary line L4 while the required driving torque T is increasingin a case where the vehicle speed V is larger than the boundary line L3.

In the meantime, a changeover from “the OUT-Connection State” to “thefirst IN-Connection State” is carried out, when the vehicle speed Vpasses through/over the boundary line L1′ while the vehicle speed V isdecreasing. A changeover from “the second IN-Connection State” to “theOUT-Connection State” is carried out, when the vehicle speed V passesthrough/over the boundary line L2′ while the vehicle speed V isdecreasing. A changeover from “the neutral state” to “the secondIN-Connection State” is carried out, (1) when the vehicle speed V passesthrough/over the boundary line L3′ while the vehicle speed V isdecreasing, or (2) when the required driving torque T passesthrough/over the boundary line L4′ while the required driving torque isdecreasing.

The reason why differences ΔV1, ΔV2, ΔV3, and ΔT4 between the boundarylines L1 and L1′, between the boundary lines L2 and L2′, between theboundary lines L3 and L3′, and between the boundary lines L4 and L4′,respectively, are provided is to suppress an occurrence of a case(so-called hunting) in which the changeover of the connection state ofthe output shaft A4 are performed frequently, when the vehicle speed Vfluctuates (increases and decreases) around each of the boundary linesL1, L2, and L3 or when the required driving torque T fluctuates(increases and decreases) around the boundary lines L4.

The boundary line L1 (low speed area) is set at a vehicle speed slightlysmaller than a vehicle speed corresponding to the shift up from the 1stgear position to the 2nd gear position. That is, the boundary line L1 isprovided at a location obtained by slightly shifting (moving) theboundary line (the solid line) corresponding to the shift up from the1st gear position to the 2nd gear position shown in FIG. 7 in adirection (leftward direction in the figure) in which the vehicle speedV decreases. Accordingly, the boundary line L1 shown in FIG. 8 has thesame shape as “the boundary line (the solid line) shown in FIG. 7”corresponding to the shift up from the 1st gear position to the 2nd gearposition.

The boundary line L2 (middle speed area) is set at a vehicle speedobtained when the rotational speed of the output shaft A4 of the M/G 40in “the OUT-Connection State” coincides with a value (e.g. a valueslightly smaller than the allowable rotational speed) determined basedon the allowable rotational speed (refer to FIG. 5). Further, in thepresent example, the boundary line L2 is located in a regioncorresponding to the 3rd gear position to the 5th gear position shown inFIG. 7. As described above, the OUT-connection reduction ratio Gout isconstant (e.g., a ratio roughly equal to the Gtm(2) in the presentexample) irrespective of the gear position of the T/M 20. Accordingly,in the OUT-Connection State, a vehicle speed at which the rotationalspeed of the output shaft A4 of the M/G 40 coincides with “the abovedescribed value determined based on the allowable rotational speed” isdetermined as a single value, irrespective of the gear position of theT/M 20. Therefore, the vehicle speed V corresponding to the boundaryline L2 shown in FIG. 8 is constant irrespective of the required drivingtorque T. That is, the boundary line L2 becomes a line extending in avertical direction in FIG. 8. The vehicle speed V corresponding to theboundary line L2 is determined based on “the OUT-connection reductionratio” and “the final reduction ratio” described above.

The boundary line L3 (high speed area) is set at a vehicle speedobtained when the energy conversion efficiency (in the driving torqueside) of the M/G 40 in “the (second) IN-Connection State” coincides witha boundary (especially at the side where the vehicle speed is larger, orthe rightward side in the figure) defining an area (refer to an areawhere fine dots are provided in FIG. 5) in which the energy conversionefficiency of the M/G 40 is larger than or equal to a predeterminedvalue (e.g., 70%).

The boundary line L4 is determined based on a torque of the drive wheelswith respect to the running resistance of the vehicle (a total sum of africtional resistance of each of various rotational members included ina driving system, a resistance to decelerate the vehicle due to a windgenerated with the running of the vehicle, and a resistance todecelerate the vehicle due to an inclination of a road, and so on).Hereinafter, the torque of the drive wheels with respect to the runningresistance of the vehicle is referred to as a “running resistancetorque”. When the running resistance torque is equal to the drivingtorque of the drive wheels, the acceleration (front-rear acceleration)of the vehicle in the front-rear direction of the vehicle becomes zero.When the driving torque of the drive wheels is larger (or smaller) thanthe running resistance torque, the front-rear acceleration becomespositive (or negative). Accordingly, the boundary line L4 is set at, forexample, a driving torque which makes the front-rear accelerationcoincide with a predetermined value (for example, zero, a positiveslight value, or a negative slight value). That is, the boundary line L4may be determined/set based on the front-rear acceleration of thevehicle or a parameter (for example, a change rate in the vehicle speed,a change rate in the rotational speed of the engine) correlating withthe front-rear acceleration of the vehicle.

The running resistance torque increases as the vehicle speed increases.Accordingly, as shown in FIG. 8, the boundary L4 increases as thevehicle speed increases. In addition, the running resistance torquebecomes larger as the upward inclination of the road is larger.Therefore, the boundary line L4 shifts more upwardly as the upwardinclination of the road is larger. When the required driving torque T islarger than a value corresponding to the boundary line L4, the conditionof the vehicle is in an acceleration condition. When the requireddriving torque T is smaller than the value corresponding to the boundaryline L4, the condition of the vehicle is in a deceleration condition.

Next will be described advantages obtained by selecting the connectionstate of the output shaft A4 of the M/G 40 as shown in FIG. 8. Notably,it is assumed that the OUT-connection reduction ratio Gout is roughlyequal to the Gtm(2), for example and just for description convenience

First, the function/effect realized by “a feature that “the (first)In-Connection State” is selected after the vehicle starts to drive whenthe vehicle speed V is zero” is described. Generally, when the vehiclestarts to drive, the gear position of the T/M 20 is set at the 1st gearposition, and the IN-connection reduction ratio Gin (=Gtm(1)) istherefore larger than the OUT-connection reduction ratio Gout.Accordingly, the driving torque, which is transmitted to the drivewheels and which is based on the output of the M/G 40, can be madelarger, compared to a case where the OUT-Connection State is selected.Consequently, a large driving torque at the drive wheels can begenerated when the vehicle starts to drive.

Next, the function/effect realized by “a feature that the boundary lineL1 is set at the vehicle speed slightly smaller than the vehicle speedcorresponding to the shift up from the 1st gear position to the 2nd gearposition” is described. When the vehicle speed passes through/over theboundary line L1 (low speed area) while the vehicle speed is increasingunder the “the (first) In-Connection State” after the start of thevehicle, the changeover from the “the (first) In-Connection State” to“the OUT-Connection State” is carried out. This changeover occurs beforethe shift up from the 1st gear position to the 2nd gear position iscarried out. In other words, the shift up from the 1st gear position tothe 2nd gear position is carried out under “the OUT-Connection State”after the changeover to the OUT-Connection State is completed. Asdescribed in the summary of the present invention, the “OUT-ConnectionState” allows the driving torque of the M/G 40 to be continuouslytransmitted to the output shaft A3 of the T/M 20 (and therefore to thedrive wheels) even during the gear position shifting operation by theT/M 20, and the shift shock can therefore be suppressed. Especially, asevere shift shock tends to occur when the gear position is changed fromthe 1st gear position to the 2nd gear position, since the change amountin the transmission reduction ratio Gtm is large. In view of the above,it is possible to remarkably moderate the shift shock which occurs whenthe gear position is changed from the 1st gear position to the 2nd gearposition by the feature described above.

Furthermore, the changeover from “the (first) In-Connection State” to“the OUT-Connection State” is carried out under the 1st gear position.That is, this changeover from “the (first) In-Connection State” to “theOUT-Connection State” is carried out while the OUT-connection reductionratio Gout (roughly equal to Gtm(2)) is smaller than the IN-connectionreduction ratio Gin (=Gtm(1)). Accordingly, this changeover decreasesthe rotational speed of the output shaft A4 of the M/G 40. It should bereminded that, as described above, the maximum torque which the M/G 40can generate becomes larger as the rotational speed of the output shaftA4 is smaller (refer to FIG. 5). Therefore, the changeover describedabove can also provide the effect that the maximum torque which the M/G40 can generate is increased.

Next will be described the function/effect realized by “a feature thatthe boundary line L2 is set at the vehicle speed obtained when therotational speed of the output shaft A4 in “the OUT-Connection State”coincides with the value determined based on the allowable rotationalspeed”. When the vehicle speed passes through/over the boundary line L2while the vehicle speed is increasing under “the OUT-Connection State”,the changeover from the “OUT-Connection State” to “the (second)IN-Connection State” is carried out. As described above, the boundaryline L2 is located in the region corresponding to the 3rd gear positionto 5th gear position shown in FIG. 7. Accordingly, this changeoveroccurs while one of the 3rd, 4th, and 5th gear positions (i.e., the gearpositions higher than or equal to the 3rd gear position) is selected.That is, this changeover occurs while the IN-connection reduction ratioGin (=one of Gtm(3), Gtm(4), and Gtm(5)) is smaller than theOUT-connection reduction ratio Gout. Accordingly, this changeover allowsthe rotational speed of the output shaft A4 of the M/G 40 to decreasefrom a value close to the allowable rotational speed (refer to amovement from a point “a” to a point “b” in FIG. 5). As a result, therotational speed of the output shaft A4 can be retained smaller than theallowable control rotational speed. In addition, the maximum torque thatthe M/G 40 can generate can be increased.

Next will be described a function/effect realized by “a feature that theboundary line L3 is set at the vehicle speed obtained when the energyconversion efficiency of the M/G 40 under “the (second) IN-ConnectionState” coincides with the boundary defining the area in which the energyconversion efficiency of the M/G 40 under “the (second) IN-ConnectionState” is larger than or equal to the predetermined value”. When thevehicle speed passes through/over the boundary line L3 while the vehiclespeed is increasing under “the (second) IN-Connection State” and under acondition where the required driving torque T is larger than theboundary line L4 (i.e., when the vehicle is in the accelerationcondition), the changeover from “the (second) IN-Connection State” to“the non-connection state” is carried out. Consequently, driving the M/G40 is stopped, and a driving torque equal to the required driving torqueT is generated only by the E/G 10. A timing at which the vehicle speedpasses through/over the boundary line L3 while the vehicle speed isincreasing (i.e., while the rotational speed of the output shaft A4 ofthe M/G 40 is increasing) means a timing at which the energy conversionefficiency of the M/G 40 passes thorough/over a part of the boundarydefining the area in which the fine dots are provided in FIG. 5, thepart being at a higher vehicle speed side (rightward side in FIG. 5)(refer to a movement from a point “b” to a point “c” in FIG. 5). Thatis, when a state of the M/G 40 has changed from a state in which theenergy conversion efficiency is larger than or equal to thepredetermined value to a state in which the energy conversion efficiencyis smaller than the predetermined value, the changeover from “the secondIN-Connection State” to “the non-connection state” is carried out. Inthe meantime, an energy generation efficiency of the E/G 10 is generallyhigh in the high speed area where the energy conversion efficiency ofthe M/G 40 is low in most cases. In this state, the total energyefficiency (fuel consumption) of the vehicles as a whole can be moreimproved by having only the E/G 10 generate the driving torque equal tothe required driving torque T than by having both the M/G 40 and the E/G10 cooperatively generate the driving torque equal to the requireddriving torque T. In view of the above, the total energy efficiency(fuel consumption) of the vehicles as a whole can be improved in a casein which the vehicle is in the acceleration condition and the energyconversion efficiency of the M/G 40 in the high speed area under “the(second) IN-Connection State” is lower than the predetermined value.

Next will be described a function/effect realized by the featuredescribed above that “the boundary L4 is set at the predetermined valueobtained when the front-rear acceleration coincides with thepredetermined value (for example, zero, a positive slight value, or anegative slight value)”. In a case where the vehicle is in theacceleration condition, it is preferable that, as described above, thechangeover from “the (second) IN-Connection State” to “thenon-connection state” be carried out when the vehicle speed passesthrough/over the boundary line L3 while the vehicle speed is increasing,in order to improve the energy conversion efficiency (fuel consumption)of the vehicle as a whole. To the contrary, in a case where the vehicleis in the deceleration condition (that is, the required driving torque Tis smaller than the boundary line L4), it is possible to supply anelectric power to the battery to store the power in the battery, theelectric power being generated by a regeneration by having the M/G 40generate the regeneration torque by retaining “the (second)IN-Connection State”. That is, in this case, selecting “the (second)IN-Connection State” instead of “the non-connection state” can moreimprove the total energy efficiency (fuel consumption) of the vehicle asa whole. In view of the above, in the case where the vehicle is in thedeceleration condition, “the (second) IN-Connection State” is preferablyretained even though the vehicle speed is larger than the valuecorresponding to the boundary line L3.

(Adjusting the Connection State Based on the Temperature of the Battery,the Temperature of the M/G, and the Remaining Battery Level)

In the present apparatus, shift amounts DL3 and DL4 are determined inaccordance with the temperature of the battery B (hereinafter, referredto as a “battery temperature”), the temperature of the M/G 40(hereinafter, referred to as a “M/G temperature”), or an amount of achemical energy (hereinafter, referred to as a “remaining batterylevel”) stored in the battery B. As shown in FIG. 8, if the DL3 ispositive, positions of the boundary lines L3 and L3′ are shifted fromthe reference (original) positions shown in FIG. 8 by the shift amountDL3 in a direction (leftward direction in FIG. 8, a direction of vehiclespeed V decrease) along which the vehicle speed V decreases. If the DL3is negative, the positions of the boundary lines L3 and L3′ are shiftedfrom the reference (original) positions shown in FIG. 8 by an absolutevalue of the shift amount DL3 (=|DL3|) in a direction (rightwarddirection in FIG. 8, a direction of vehicle speed V increase) alongwhich the vehicle speed V increases. As shown in FIG. 8, if the DL4 ispositive, positions of the boundary lines L4 and L4′ are shifted fromthe reference (original) positions shown in FIG. 8 by the shift amountDL4 in a direction (downward direction in FIG. 8, a direction ofrequired driving torque T decrease) along which the required drivingtorque T decreases. If the DL4 is negative, the positions of theboundary lines L4 and L4′ are shifted from the reference (original)positions shown in FIG. 8 by an absolute value of the shift amount DL4(=|DL4|) in a direction (upward direction in FIG. 8, a direction ofrequired driving torque T increase) along which the vehicle speed Vincreases. Hereinafter, the shift amounts DL3 and DL4 may also beexpressed as and represented by “DL*” (wherein * is “3” or “4”.

FIG. 9 is a graph showing a relation between the battery temperature andthe shift amount DL*a (one of DL3 and DL4). As shown in FIG. 9, theshift amount DL*a is zero (i.e., corresponding to the originalpositions) when the battery temperature is equal to a value T1 (thebattery temperature=T1). The shift amount DL*a increases from zero asthe battery temperature increases when the battery temperature is higherthan the value T1 (the battery temperature>T1). The shift amount DL*adecreases from zero as the battery temperature decreases when thebattery temperature is lower than the value T1 (the batterytemperature<T1). The shift amounts DL3 a may be the same as or differentfrom the shift amount DL4 a, each varying depending on the batterytemperature. The battery temperature can be obtained from an output ofthe battery temperature sensor 68.

FIG. 10 is a graph showing a relation between the M/G temperature andthe shift amount DL*b (one of DL3 and DL4). As shown in FIG. 10, theshift amount DL*b is zero (i.e., corresponding to the originalpositions) when the M/G temperature is equal to a value T2 (the M/Gtemperature=T2). The shift amount DL*b increases from zero as the M/Gtemperature increases when the M/G temperature is higher than the valueT2 (the M/G temperature>T2). The shift amount DL*b decreases from zeroas the M/G temperature decreases when the M/G temperature is lower thanthe value T2 (the M/G temperature<T2). The shift amounts DL3 b may bethe same as or different from the shift amount DL4 b, each varyingdepending on the M/G temperature. The M/G temperature can be obtainedfrom an output of the M/G temperature sensor 69.

FIG. 11 is a graph showing a relation between the remaining batterylevel and the shift amount DL*c (one of DL3 and DL4). As shown in FIG.11, the shift amount DL*c is zero (i.e., corresponding to the originalpositions) when the remaining battery level is equal to a value V1 (theremaining battery level=V1). The shift amount DL*c increases from zeroas the remaining battery level increases when the remaining batterylevel is higher/larger than the value V1 (the remaining batterylevel>V1). The shift amount DL*c decreases from zero as the remainingbattery level decreases when the remaining battery level issmaller/lower than the value V1 (the remaining battery level<V1). Theshift amounts DL3 c may be the same as or different from the shiftamount DL4 c, each varying depending on the remaining battery level. Theremaining battery level can be obtained according to one of well knownmethods.

The shift amount DL*may be one of the DL*a itself, the DL*b itself, andthe DL*c itself. The shift amount DL* may be a value calculated based ontwo or more of the DL*a, the DL*b, and the DL*c (e.g., the shift amountDL* may be an average of two or more of the DL*a, the DL*b, and theDL*c).

By determining the shift amount DL* as described above, in FIG. 8, theneutral area is expanded (enlarged, becomes wider/larger), andsimultaneously the second IN-Connection area is narrowed (becomesnarrower/smaller), as the battery temperature is higher, or as the M/Gtemperature is higher, or as the remaining battery level is larger(higher). That is, a possibility of selecting the neutral state (an easeby which the neutral state is selected, or the possibility that theneutral state is selected) becomes higher, as the battery temperature ishigher, or as the M/G temperature is higher, or as the remaining batterylevel is larger (higher).

Next will be described a function/effect realized by the featuredescribed above. In the neutral state, unlike in the IN-Connection Stateand in the OUT-Connection State, the rotation of the output shaft of theM/G 40 is stopped, because driving the M/G 40 as the power source isstopped and driving the M/G 40 as the electric motor generator isstopped. Accordingly, in the neutral state, the increase in the batterytemperature as well as the increase in the M/G temperature can besuppressed, and the battery B is not charged.

In the meanwhile, in order to protect the battery B and the M/G, etc.,it is preferable that the M/G 40 be operated/controlled (as the powersource or the electric motor generator) in such a manner that thebattery temperature and the M/G temperature do not become excessivelyhigh. Further, it is unlikely that the battery B needs to be furthercharged, when the remaining battery level is sufficiently large/high.Accordingly, when the battery temperature is high, or when the M/Gtemperature is high, or when the remaining battery level is large/high,it is preferable that a time period in which the neutral state isselected/realized be lengthened (i.e., a frequency and/or a possibilityof selecting/realizing the neutral state be made larger).

As described above, in the present apparatus, a possibility ofselecting/realizing the neutral state increases, as the batterytemperature is higher, or as the M/G temperature is higher, or as theremaining battery level is larger. Accordingly, a time period in whichthe neutral state is selected/realized lengthens, when the batterytemperature or the M/G temperature is high, or when the remainingbattery level is large/high. Consequently, the increase in the batterytemperature as well as the increase in the M/G temperature can besuppressed, and the further unnecessary charging of battery B can bealso avoided.

As described above, the vehicular power transmission control apparatusaccording to the embodiment of the present invention is applied to thevehicle comprising, as power sources, the E/G 10 and the M/G 40, andfurther comprising the so-called automated manual transmission utilizingthe T/M 20 which does not comprise a torque convertor. The apparatuscomprises the changeover mechanism 50 which can select, as the (anactual) connection state of the output shaft A4 of the M/G 40, one of“the IN-Connection State”, “the OUT-Connection State”, and “thenon-connection state”. The IN-Connection State is the state in which thepower transmission path between the input shaft A2 of the T/M 20 and theoutput shaft A4 of the M/G 40 is provided/made/realized. TheOUT-Connection State is the state in which the power transmission pathbetween the output shaft A3 of the T/M 20 and the output shaft A4 of theM/G 40 is provided/made/realized. The non-connection state is the statein which no power transmission path among these shafts isprovided/made/realized. The selection for the connection state is madebased on the combination (area) of the vehicle speed V and the requireddriving torque T. As for the changeovers, as the battery temperature ishigher, or as the M/G temperature is higher, or as the remaining batterylevel is larger, the neutral area is enlarged, and accordingly, thepossibility of selecting “the neutral state” increases (i.e., the easeby which “the neutral state” is selected is increased, or the frequencyof selecting “the neutral state” is increased). Consequently, theincrease in the battery temperature as well as the increase in the M/Gtemperature can be suppressed, and the further unnecessary charging ofbattery B can also be avoided.

The present invention is not limited to the embodiment described above,but may be modified as appropriate without departing from the scope ofthe invention. For example, the so-called automated manual transmissionwhich uses the multiple gear ratio transmission but which does notinclude a torque converter is used as the transmission, however, amultiple gear ratio transmission or a continuously variable transmission(a so-called automatic transmission (AT)) may be used as thetransmission, each including a torque convertor and automaticallyperforming an operation for a gear position change in accordance withthe vehicle driving condition. In this case, the C/T 30 is omitted.

Further, a transmission (a so-called manual transmission (MT)) may beused as the transmission, the manual transmission being a multiple gearratio transmission without the torque converter, performing an operationfor a gear position change directly (without using an actuator) by anoperation of a link mechanism caused by an operating force supplied tothe shift lever from the driver.

Further, in the embodiment described above, the changeover mechanism 50is configured so as to be able to select any one from “the IN-ConnectionState”, “the OUT-Connection State”, and “the neutral state(non-connection state)”, however, the changeover mechanism 50 may beconfigured so as to be able to select any one from only “the neutralstate and the IN-Connection State”. In this case, the boundary lines L1,L1′, L2 and L2′ shown in FIG. 8 are omitted so that the OUT-Connectionarea in FIG. 8 and the first and second IN-Connection areas areunited/merged into a single IN-Connection area. Furthermore, thechangeover mechanism 50 may be configured so as to be able to select anyone from only “the neutral state” and “the OUT-Connection State”. Inthis case, the boundary lines L1, L1′, L2, and L2′ shown in FIG. 8 areomitted so that the OUT-Connection area shown in FIG. 8 and the firstand second IN-Connection areas shown in FIG. 8 are united/merged into asingle OUT-Connection area.

Further, in the embodiment described above, the connection state of theoutput shaft A4 of the M/G 40 is selected/determined based on thecombination of the vehicle speed V and the required driving torque T(refer to FIG. 8), but the connection state of the output shaft A4 ofthe M/G 40 may be selected/determined based on a combination of “any onefrom the vehicle speed V, the rotational speed of the output shaft A1 ofthe E/G 10, the rotational speed of the input shaft A2 of the T/M 20,and the rotational speed of the output shaft A4 of the M/G 40” and “anyone from the required driving torque T, the operation amount of theacceleration pedal AP, and the opening degree of a throttle valve (notshown) disposed in an intake passage of the E/G 10”. The opening degreeof the throttle valve may be obtained from a throttle valve openingdegree sensor 64. The rotational speed of the output shaft A1 of the E/G10, the rotational speed of the input shaft A2 of the T/M 20, and therotational speed of the output shaft A4 of the M/G 40 may be obtainedfrom a rotational speed of the engine output shaft sensor 65, arotational speed of the transmission input shaft sensor 66, and arotational speed of the electric motor output shaft sensor 67,respectively.

Further, in the embodiment described above, (1) when the batterytemperature is higher than or equal to a first predetermined value(which is considerably higher than the value T1 shown in FIG. 9), or (2)when the M/G temperature is higher than or equal to a secondpredetermined value (which is considerably higher than the value T2shown in FIG. 10), the boundary lines L3, L3′, L4 and L4′ shown in FIG.8 may be omitted as shown in FIG. 12 so that the second IN-Connectionarea is united/merged into the neutral area. This allows a period inwhich the second IN-Connection state is selected to be changed into aperiod in which the neutral state is selected, and the period in whichthe neutral state is selected thereby lengthens. Consequently, when thebattery temperature or the M/G temperature is considerably high, afurther increase in the battery temperature as well as a furtherincrease in the M/G temperature can be suppressed with certainty, sothat the battery B or the M/G 40 can be protected with certainty.

Similarly, in the embodiment described above, (1) when the batterytemperature is higher than or equal to a first predetermined value(which is considerably higher than the value T1 shown in FIG. 9), or (2)when the M/G temperature is higher than or equal to a secondpredetermined value (which is considerably higher than the value T2shown in FIG. 10), the apparatus may be configured to select only theneutral state as shown in FIG. 13, irrespective of (without dependingon) the vehicle speed V and the required driving torque T. According tothis configuration, the further increase in the battery temperature aswell as the further increase in the M/G temperature can be suppressedwith certainty, so that the battery B or the M/G 40 can be protectedwith certainty.

Further, in the embodiment described above, the shift amounts DL*a,DL*b, and DL*c, each used for calculation of the shift amount DL* forthe positions of the boundary lines L3 and L4, are set in such a mannerthat the shift amounts DL*a, DL*b, and DL*c are varied continuously inaccordance with the battery temperature, the M/G temperature, and thebattery remaining level, respectively (refer to FIGS. 9-11). However, asshown in FIG. 14 corresponding to FIG. 9, the shift amount DL*a may beset so as to be maintained at zero (DL*a=0) when the battery temperatureis within a predetermined range (so-called dead zone) including thevalue T1 at which the shift amount DL*a is zero. Similarly, as shown inFIG. 15 corresponding to FIG. 10, the shift amount DL*b may be set so asto be maintained at zero (DL*b=0) when the M/G temperature is within apredetermined range (so-called dead zone) including the value T2 atwhich the shift amount DL*b is zero. Similarly, as shown in FIG. 16corresponding to FIG. 11, the shift amount DL*c may be set so as to bemaintained at zero (DL*c=0) when the battery remaining level is within apredetermined range (so-called dead zone) including the value V1 atwhich the shift amount DL*c is zero. Further, the shift amounts DL*a,DL*b, and DL*c may be set so as to be varied in a stepwise fashion (witha single step, or with two steps or more) in accordance with the batterytemperature, the M/G temperature, and the battery remaining level,respectively.

Further, in the embodiment described above, the positions of theboundary lines L3 and L4 are varied in accordance with the batterytemperature, the M/G temperature, and the battery remaining level,however, only one of positions of the boundary lines L3 and L4 may bevaried. Furthermore, in the embodiment described above, the positions ofthe boundary lines L3 and L4 are changed so as to be shifted in parallelin FIG. 8 (i.e., the boundary lines L3 and L4 are shifted in such amanner that a slope of each of the boundary lines L3 and L4 with respectto the coordinate axes remains unchanged), however, the positions of theboundary lines L3 and L4 may be shifted in a different fashion from theparallel-shift (i.e., the boundary lines L3 and L4 may be shifted insuch a manner that a slope of each of the boundary lines L3 and L4 withrespect to the coordinate axes does not remain the same).

Further, the embodiment described above is configured in such a mannerthat it obtains the boundary lines L1-L4 from the single map (refer toFIG. 8) and it changes/shifts the positions of the obtained boundarylines L3 and L4, when changing the positions of the boundary lines L3and L4 in accordance with “the battery temperature, the M/G temperature,or the battery remaining level”. To the contrary, the target connectionstate of the output shaft A4 of the M/G 40 may be selected as follows.

(1) The apparatus stores a plurality of maps A-E shown in FIGS. 17-21,respectively, each corresponding to FIG. 8. Each of the maps correspondsto each of one selected from “the battery temperatures, the M/Gtemperatures, and the battery remaining levels” different from to oneanother (that is, each of the maps A-E defines the positions of theboundary lines L1-L4 for each of one of the “battery temperatures, theM/G temperatures, and the battery remaining levels”, and the positionsof the boundary lines L3 and L4 in any one of the maps is different fromthose in another of the maps).(2) The apparatus selects one of the maps A-E, the selected mapcorresponding to (or being in accordance with) the current value of “thebattery temperature, the M/G temperature, or the battery remaininglevel”.(3) The apparatus selects the target connection state of the outputshaft A4 of the M/G 40 based on the selected map.

It can be understood from FIGS. 17-21, the map A has the narrowestneutral area among the maps A-E. In other words, the map A provides thelowest possibility of selecting the neutral state. The map E has thewidest neutral area among the maps A-E. In other words, the map Eprovides the highest possibility of selecting the neutral state. Inaddition, the neutral area in the map B is wider than one in the map A,the neutral area in the map C is wider than one in the map B, theneutral area in the map D is wider than one in the map C, and theneutral area in the map E is wider than one in the map D. In otherwords, the possibility of selecting the neutral state according to themap B is higher than one according to the map A. The possibility ofselecting the neutral state according to the map C is higher than oneaccording to the map B. The possibility of selecting the neutral stateaccording to the map D is higher than one according to the map C. Thepossibility of selecting the neutral state according to the map E ishigher than one according to the map D. When using these maps, as shownin FIG. 22, one of “the battery temperature, the M/G temperature, andthe battery remaining level” is divided into five areas (regions). Themap A, the map B, the map C, the map D, and the map E is selected inthis order, with an increase in one of “the battery temperature, the M/Gtemperature, and the battery remaining level” from its possiblelowest/smallest value. That is, the map having the wider neutral area(or the map providing the higher possibility of selecting the neutralstate) is selected, as one of “the battery temperature, the M/Gtemperature, and the battery remaining level” is higher/larger.

1. A vehicular power transmission control apparatus applied to a vehicle comprising an internal combustion engine and an electric motor as power sources, comprising: a transmission including an input shaft to provide a power transmission path between said input shaft of said transmission and an output shaft of said internal combustion engine, and an output shaft to provide a power transmission path between said output shaft of said transmission and drive wheels of said vehicle, wherein said transmission is capable of adjusting a transmission reduction ratio which is a ratio of a rotational speed of said input shaft of said transmission to a rotational speed of said output shaft of said transmission; a changeover mechanism which is capable of changing a connection state of an output shaft of said electric motor to any one from alternatives comprising two or more of an input-side-connection state, an output-side-connection state, and a non-connection state as an essential state, said input-side-connection state being a state in which a power transmission path is provided between said output shaft of said electric motor and said input shall of said transmission, said output-side-connection state being a state in which a power transmission path is provided between said output shaft of said electric motor and said drive wheels without involving said transmission, and said non-connection state being a state in which neither a power transmission path between said output shaft of said electric motor and said input shaft of said transmission, nor a power transmission path between said output shaft of said electric motor and said output shaft of said transmission is provided; state-representing-amount obtaining means for obtaining, as a state-representing-amount or as state-representing-amounts, one or more of a temperature of a battery which supplies an electric energy to said electric motor, a temperature of said electric motor, and a battery remaining level indicative of an amount of an energy stored and remained in said battery; and control means for selecting a target connection state of said output shaft of said electric motor from said connection states which said changeover means can realize, based on said obtained state-representing-amount or said state-representing-amounts and a parameter indicative of a running condition of said vehicle other than said state-representing-amount or said state-representing-amounts, in such a manner that an amount of time that said non-connection state is selected varies, and for controlling said changeover means in such a manner that an actual connection state of said output shaft of said electric motor coincides with said connection state selected as said target connection state.
 2. A vehicular power transmission control apparatus according to claim 1, wherein said control means is configured so as to: change said actual connection state of said output shaft of said electric motor from a connection state other than said non-connection state to said non-connection state, when a value correlating with a speed of said vehicle as said parameter passes over a threshold while said value correlating with a speed of said vehicle is increasing; and adjust said threshold in such a manner that said threshold becomes smaller, as said temperature of said battery is higher, or as said temperature of said electric motor is higher, or as said remaining battery level is larger.
 3. A vehicular power transmission control apparatus according to claim 1, wherein said control means is configured so as to: change said actual connection state of said output shaft of said electric motor from a connection state other than said non-connection state to said non-connection state, when a value correlating with a required driving torque as said parameter passes over a threshold while said value correlating with a required driving torque is increasing, said value correlating with a required driving torque being a value obtained based on an operation applied to an acceleration operating member by a driver of said vehicle; and adjust said threshold in such a manner that said threshold becomes smaller, as said temperature of said battery is higher, or as said temperature of said electric motor is higher, or as said remaining battery level is larger.
 4. A vehicular power transmission control apparatus according to claim 2, wherein said control means is configured so as to always fix said actual connection state of said output shaft of said electric motor to said non-connection state, when said temperature of said battery is higher than or equal to a first predetermined value, or when said temperature of said electric motor is higher than or equal to a second predetermined value.
 5. A vehicular power transmission control apparatus according to claim 1, wherein said control means is configured so as to: change said actual connection state of said output shaft of said electric motor from said input-side-connection state to said output-side-connection state, when a value correlating with a speed of said vehicle as said parameter passes over a first threshold while said value correlating with a speed of said vehicle is increasing; change said actual connection state of said output shaft of said electric motor from said output-side-connection state to said input-side-connection state, when said value correlating with a speed of said vehicle passes over a second threshold larger than said first threshold while said value correlating with a speed of said vehicle is increasing; change said actual connection state of said output shaft of said electric motor from said input-side-connection state to said non-connection state, (1) when said value correlating with a speed of said vehicle passes over a third threshold larger than said second threshold while said value correlating with a speed of said vehicle is increasing in a case where a value correlating with a required driving torque as said parameter is larger than a fourth threshold, said value correlating with a required driving torque being a value obtained based on an operation applied to an acceleration operating member by a driver of said vehicle, or (2) when said value correlating with a required driving torque passes over said fourth threshold while said value correlating with a required driving torque is increasing in a case where said value correlating with a speed of said vehicle is larger than said third threshold; and adjust at least one of said third threshold and said fourth threshold in such a manner that said third threshold becomes smaller and said fourth threshold becomes smaller, as said temperature of said battery is higher, or as said temperature of said electric motor is higher, or as said remaining battery level is larger.
 6. A vehicular power transmission control apparatus according to claim 5, wherein said control means is configured so as to fix said actual connection state of said output shaft of said electric motor to said non-connection state, in a condition in which said value correlating with a speed of said vehicle is larger than or equal to said second threshold, (1) when said temperature of said battery is higher than or equal to a first predetermined value, or (2) when said temperature of said electric motor is higher than or equal to a second predetermined value.
 7. A vehicular power transmission control apparatus according to claim 5, wherein said control means is configured so as to always fix said actual connection state of said output shaft of said electric motor to said non-connection state, irrespective of said value correlating with a speed of said vehicle and said value correlating with a required driving torque, (1) when said temperature of said battery is higher than or equal to a first predetermined value, or (2) when said temperature of said electric motor is higher than or equal to a second predetermined value.
 8. A vehicular power transmission control apparatus according to claim 1, further comprising a clutch mechanism, disposed between said output shaft of said internal combustion engine and said input shaft of said transmission, for at least one of breaking and providing a power transmission path between said output shaft of said internal combustion engine and said input shaft of said transmission by disengaging and engaging said clutch mechanism, respectively, and wherein, said transmission is a multiple gear ratio transmission which does not comprise a torque converter and which can realize each of a plurality of predetermined reduction ratios different from one another as said transmission reduction ratio, and said control means is configured so as to control, based on a driving condition of said vehicle, the at least one of breaking and providing of said power transmission path by disengaging and engaging said clutch mechanism, respectively, and so as to control said transmission reduction ratio. 